How much does commercial solar cost in the UK?

There's no single answer here, because commercial solar cost is driven far more by site-specific factors than by a simple £/kWp headline figure. That said, the main drivers are consistent across almost every project, and knowing them makes it much easier to sanity-check quotes.

What actually drives the cost

• System size and roof type — larger systems generally have a lower cost per kWp, but a complex or aged roof (multiple pitches, existing penetrations, structural reinforcement needed) can push costs up regardless of size.
• Grid connection — if your site needs a distribution network operator (DNO) upgrade to export or use the generation you're planning, that can be one of the largest single line items, and it's easy to miss in an early estimate.
• Roof condition and access — scaffolding, working at height requirements, and whether the roof needs remedial work before installation all affect labour cost significantly.
• Inverter and mounting choice — string vs. optimised systems, and ballasted vs. penetrative mounting, trade off upfront cost against long-term performance and roof warranty implications.
• Battery storage, if included — adding BESS increases upfront cost substantially, and whether it pays for itself depends heavily on your load profile and tariff structure (see our BESS payback guide).

Questions worth asking before you get quotes

• What roof survey has actually been done, or is this a desktop estimate?
• Is a DNO application included in the quote, or a separate cost?
• What's the assumed system loss percentage, and is it justified for your roof orientation and shading?
• What ongoing maintenance is included, and for how long?
• What happens to the warranty if something else on the roof needs work later?

The honest starting point

Before spending money on formal quotes, a postcode-based generation and payback estimate gets you a realistic starting range in minutes. Try our solar payback calculator — it uses real solar irradiance data (PVGIS) for your location, not a flat national average.